The relationship between clinical evidence of anthracycline cardiotoxicity and histologic signs of anthracycline cardiotoxicity was evaluated by reviewing the clinical and morphologic finding in 64 patients studied at necropsy, all of whom had received doxorubicin or daunorubicin chemotherapy during life. Of the 64 patients, 20 (31%) had documented clinical toxicity consisting of impaired left ventricular systolic performance: in 7 (35%) of these 20 patients, histologic signs of toxicity were absent. In the remaining 13 patients, histologic signs of toxicity ranged from mild to severe. Of the 44 (69%) patients without clinical signs of drug toxicity, 21 (48%) had no histologic signs of cardiotoxicity.